To assess the safety and efficacy of two dose levels(maximum total dose 4 mg/kg lbw of b9420-001 in the pharmaceutical formulation 1 mg b9420-001 rsp-c is applied with 50 mg phospholipids) in the treatment of adults with the acute respiratory distress syndrome in comparison to standard therapy. To assess the composition and function of surfactant recovered from bronchoalveolar lavage (bal) fluid.